diff --git a/conf/machine/sysmobts2100.conf b/conf/machine/sysmobts2100.conf
index 4ac183b..04d5463 100644
--- a/conf/machine/sysmobts2100.conf
+++ b/conf/machine/sysmobts2100.conf
@@ -23,4 +23,4 @@ MACHINE_EXTRA_RDEPENDS = "\
 	task-sysmocom-bts \
 	${@['watchdog', ''][d.getVar('VIRTUAL-RUNTIME_init_manager', True) == 'systemd']} \
 	"
-EXTRA_IMAGEDEPENDS = "sysmobts2100-devtools"
+EXTRA_IMAGEDEPENDS += "sysmobts2100-devtools"